Inclosed furnace



March 24, 1925 c. STEENSTRUP Incnossn FURNACE F541 pt. 23, 1922 .N M ME entor wt. 3% m B hf m r t o s W M t s 5 .ln i H m c Patented Mar. 24, 1925.

UNITED STATES CHRISTIAN STEENSTRUP, F SCHENECTADY, NEW YORK,

ASSIGNOR TO GENERAL ELECTRIC COMPANY. A CORPORATION OF NEW YORK.

INCLOSED FURNACE.

Application filed September 23, 1922. Serial No. 590,007.

T 0 all whom it may concern:

Be it known that I, CHRISTIAN STEaN- STRUP, a citizen of the United States, residing in Schenectady, in the county of Schenectady, State of New York, have invented certainnew and useful Improvements in Inclosed Furnaces, of which the following is a specification.

The present invention comprises an improvement in inclosed furnaces, and particularly in electric furnaces, in which the work is surrounded by a selected gas during the operation of the furnace, and also in the method .of operating the same.

Certain metallurgical operation, for example, the uniting of metal parts by fusion of copper or other metals, in the presence of a reducing gas, are carried out in an inclosed space in large electric furnaces which are Well heat-insulated. After the opera-- tion is completed a long time, sometimes several days, has been required to cool down the furnace and its contents and hence the output of the furnace has been very seriously restricted and the cost of the product has been correspondingly increased.

A slow rate of cooling in some cases is disadvantageous in its effect upon the work. For examp e, when unitin metal parts by fused-copper, silver, or the Iike, in h drogen, it is desirable to cool the work rapi 1y when the union is complete, particularly from the highest temperature down to a point where further alloyage or other undesired action stops.

In accordance with my invention, greater efliciency and economy of operation of gasfilled furnaces is obtained by utilizing the same gas which is necessary to the metallurgical operation as a cooling medium. This is accomplished by establishing a circulation of said gas through the furnace and cooling means afterthe heat-treating process has been completed. As a result of my in' vention a complete operation can be carried out in a large industrial furnace in less than one-fourth of the time formerly re quired.

As a further consequence of my invention, an improved product can be roduced, particularly when coating or uniting metal by fused copper.

In the accompanying drawing, Fig. 1 is a plan view of an apparatus embodying my invention, part of the furnace cover being broken away to show the elements, and Fig. 2 a slight modification.

Referring to the drawing, the apparatus comprises a closed metal container 1 lined with suitable refractory heat-insulating materials and containing suitable heating electric heating IS a vertical section of means, as for example, electric resistors 2.

Inlet and outlet pipes 3 and 4, respectively, are provided for admitting and carrying away gas, as for example, hydrogen. During the heating operation or working period of the furnace, sufficient gas is supplied to provide a slight excess so as to produce a low pressure in the confined work-containing space or chamber. During operation with a combustible gas, such as hydrogen, some gas is permitted to burn at the outlet pipe 4 to indicate whether or not a suitable pressure exists in the apparatus. The cover 5 of the furnace which during the working period is held down by bolts or clamps is removable by elevating devices engaging with the ears 6. Valve tubes 7 containing sight glasses communicate with the furnace interior to permit observation of the furnace interior. Thermo-couples may be inserted into the furnace through tubes 8.

Connected to the furnace by conduits 9 and 10 is a cooler comprising a plurality of pipes 11 located in a casing 12 A circulation of cooling water about the pipes 11 in the casing 12 is maintained by means of the inlet and outlet pipes 13 and 14-.

During the period that the work is heated to carry out desired operations, as for example, the union of metal parts in hydrogen by "fusion of metal. the valves 15 and 16 in the conduits 9 and 10 are closed to prevent the circulation of the gas through the cooler. After the work of the furnace is completed the supply of current to the resistors 2 is interrupted. To lower the temperature of the furnace the valves 15 and 16 are opened and a blower or pump 17 is put into operation. The blower may be driven by any suitable means, a shaft 18 being shown for the purpose. Due to the pump, the hydrogen or other selected gas is circulatcd through the pipes 11 where it gives up heat to the cooling fluid. During the cooling or temperature reducing period of the furnace the supply of hydrogen thereto is maintaincd. \Vhcn the temperature has been lowered to a desired point,

the Valves 15 and 16 are closed, the furnace metal so as to stop alloying action, which,-

particularly in the case of some metals, would tend to cause deterioration of the union or joint. With this in view the pump may be driven rapidly at the start and later on at a decreased rate if a slower cooling operation is desired.

In Fig. 1 I have shown the conduits 9 and 10 leading to and from the cooler as being connected at substantially diametrically opposite points to the container, and for many kinds of work this is entirely satisfactory. There are other kinds of work, however, for which this is not the most advantageous arrangement. For example, in the copper brazing of parts which are placed one over the other in the container and where the center portion of each part is more lnassive than its peripheral portion. \Vhere such is the case, I tind it preferable to deliver the gas from the cooler to the container at some central point from which the gas flows first over the massive portion of the work and then over the lighter portion. To more effectively direct the cool gas battles of any suitable character may be employed. In Fig. 2 is shown a construction suitable for the last-mentioned class of work, 1 indicates the heat-insulated container which is provided with suitable heating means as before, and 20 a brick work foundation. 21 indicates the work or parts to be brazed or otherwise treated which may for example, be turbine diahragms or wheels which are more massive 1n the center than at the periphery. parts may be supported within the container in any suitable manner. The gas from the cooler enters the container by the conduit 10 and flows directly downward striking the work at the center where the mass is greatest. Vhere the mass is greatest at the" periphery a conical deflector or bafiie 22 is preferably employed to deflect the gas from the center toward the eriphery. In the brick work is a. con uit 23 which is connected to the cpnduit 9 leading to the pump associated with the cooler. Above t baffle plate 24 which servesto direct the gas from the center outwardly and thus prevent it from shunting more or less directly from the inlet to the outlet. By the use of the means described, the parts within the container may be cooled in such manner as to avoid undue strains in the parts as they are cooled.

I particularly wish to emphasize the fact that whereas the reducin gas was formerly used for one purpose on y, i. e. to assist in e opening of the. conduit 23 is a carrying out a metallurgical process, it is now used not only for that purpose, but also to reduce the temperature of the furnace and of the work or charge contained there in. It is also to be noted that the use of said gas prevents the entrance of air to the furnace during both operations.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is

1. An apparatus for carrying out operations in the presence of a selected gas comprising a heating chamber, a cooling device, conduits connecting said heating chamber with said cooling device, and means for circulating said gas from said heating chamber to said cooling device and from said cooling device to said heating chamber.

2. An apparatus for carrying out heating operations in a as in an enclosed space comprising a sealed receptacle, means for supplying a gas thereto, heating means therefor, conduits adapted to convey gas connected at opposite ends to said receptacle to permit the circulation of gas therethrough, and means for carrying away heat from said conduits.

3. An apparatus for carrying out thermal operations in a confined space which comprises means for surrounding the charge during the heating operation by a selected gas, means for restricting the escape of heat from said as during the heating 0 eration, and contro lable means for artificia ly cooling the charge through the intermedlary of said as during the cooling operation.

4. In an apparatus for the purpose described, the combination of a container for the charge, heating means therefor, means for maintaining asupply of selected gas in the container durin its working period, and means for with rawing said gas from the container after the working period is completed, cooling the same and returning it to the container to reduce its temperature and also that of the charge therein.

5. An apparatus for the purpose described which comprises a container for the charge, heating means therefor, means for supplying-a selected gas to the container during its working period, a cooling means which is connected to the container at suitably spaced points, and means for circulating the gas through the container and cooler after said working period is completed for the purpose of reducing the temperature of the container and of the charge therein.

6. An apparatus for the purpose described WhlCh comprises a container for the charge, heating means therefor, means for supp ying a selected gas to the container during its working period. a cooling means, conduits connecting the cooling means to the container at suitably spaced points, means for preventing the circulation of gas through the conduits during the working period of the container, and means for maintaining a forced circulation of said gas through the container and cooling means after said working period for the purpose of reducing the temperature of the container and of the charge therein.

7. In an apparatus of the character described the combination of a container for the charge, heating means therefor, means 'for supplying a selected gas to the container during its working period, a cooler which is inactive during said period, conduits connecting the cooler with the container at suitably spaced points, means for causing a circulation of said gas through the container and cooler after the working period is completed, and means for directing the flow of gas over the charge Within the container during the cooling period.

8. An apparatus for reducing the temperature of a charge which has been subjected to high temperatures during the working period which comprises a closed container in which the charge is located and is surrounded by a selected gas, a means for absorbing heat from the charge through the intermediary of the gas, and conduits for circulating a cooling fluid through said means.

- 9. The method of cooling a heated charge in a closed heating chamber containing a selected gas which consists in circulatlng said gas successively through said chamber and a zone maintained at a lower temperature.

10. The method of cooling a closed heating chamber containing a selected gas which consists in withdrawing said gas from said chamber, cooling said as, and then returning the cooled gas to said chamber.

11. The method of cooling a high temperature closed furnace which contains a charge and also a selected as which comprises establishing communication between the furnace and a cooler, and thereafter maintaining a forced circulation of said selected gas through the cooler and over the charge.

In witness whereof, I have hereunto set my .hand this 22nd day of September, 1922.

CHRISTIAN STEENSTRUP. 

